Anchoring devices are often used in construction work to provide fall protection to the workers. A worker will arrange to be tethered or tied, usually through a lanyard connected to a harness worn by the worker, to the anchoring device. The anchoring device itself is typically anchored to the structure being constructed, and is provided as a safety precaution to minimize the distance the worker might fall from the structure.
The lanyard and harness both will also stretch to some extent in the event the worker falls and thereby absorb some energy, which will reduce the peak forces experienced by the worker as the worker reaches the end of the fall. In addition, add-on energy absorbing devices are sometimes provided, which may be coupled to any of the anchoring device, the lanyard, or the harness, to further reduce these forces.
Anchoring devices specifically for mounting to wood structures, such as roofs, are also known in the art. They are typically screwed down through a plywood sheet into the thin side of a length of nominal 2×6 or 2×8 dimensional lumber that forms part of a truss. The thin side of a 2×“Y” piece of dimensional lumber is actually only 1½ inches wide. Since the loading on the anchoring device, if a worker who is tethered to the anchoring device falls, can be in any direction, in the worst case it could be applied transverse to the thin side. In that case the threaded shafts of the screws sunk into the wood would pry against a relatively thin section of wood, typically less than ¾ inches of thickness if the screws are disposed mid-way along the 1½ side, and would therefore more readily fracture or split the wood and tear out.